As an ultrasound system has noninvasive and nondestructive characteristics, it is widely used in medical applications for obtaining information about the internal structure of an object. The ultrasound system provides in real time a high-resolution image of an internal tissue of an object to a medical practitioner, without requiring a surgical operation to directly make an incision in the body to observe the object.
Generally, in a state where a probe contacts a surface of an object, the ultrasound system transmits an ultrasound signal to the object and receives an ultrasound signal (hereinafter referred to as an echo signal) reflected from the object. The ultrasound system generates an ultrasound image of the object, based on the echo signal received through the probe and displays the generated ultrasound image in a display. The ultrasound image is expressed as a brightness (B) mode image using a reflection coefficient based on an acoustic impedance difference between tissues.
A carotid artery among a plurality of blood vessels included in the human body is a blood vessel that connects a main artery to a brain blood vessel, and there are two carotid arteries which are respectively disposed on the left and the right of the neck. About 80% of blood flowing to the brain passes through the carotid artery. A carotid artery examination using the ultrasound system is a useful examination method that accurately evaluates a degree of stenosis of the carotid artery.
Generally, an image of one slice of a blood vessel is used for diagnosing a degree of stenosis of the blood vessel. However, it is difficult to know an overall degree of stenosis of a blood vessel by using only an image of one slice of the blood vessel.